Reversible heat pump system



Jan. 31, 1961 Filed May 19, 1959 J. A. SALTER REVERSIBLE HEAT PUMPSYSTEM 2 Sheets-Sheet 1 INVENTOR.

ATTOFi/VEX Jan. 31, 1961 J. A. SALTER 2,969,655

REVERSIBLE HEAT PUMP SYSTEM Filed May 19, 1959 2 Sheets-Sheet 2 ATTORNEYUnited States Patent REVERSIBLE HEAT PUMP SYSTEM James A. Salter, FortLauderdale, Fla., assignor to Ranco Incorporated, Columbus, Ohio, acorporation of Ohio Filed May 19, 1959, Ser. No. 814,233

5 Claims. (Cl. 62-324) The present invention relates to improvements inreversible heat pump systems of the type comprising a refrigerantcompressor connected in a refrigerating circuit including two heatexchangers, either of which may function as a condenser or anevaporator, depending on the order of flow of refrigerant therethrough,one exchanger arranged to temper the air of a certain area, such as in aroom, and the other exchanger arranged to dissipate or absorb heat fromair of another area, such as out-ofdoors, and means for reversing theorder of flow of refrigerant through the exchangers.

It is well known in the refrigeration art that an enclosure, such as aroom, can be either cooled or heated by discharging air thereinto whichhas been passed over a heat exchanger, sometimes referred to as theindoor coil, of a reversible heat pump of the type'referred to. Coolingof the room is efiected-when the inside coil functions as an evaporatorand heating is effected when this coil functions as a condenser. It isalso known that for most efiicient operation of such systems, thevolumetric capacity of .the inside coil should be approximatelytwo-thirds that of the other exchanger, sometimes referred to as theoutside coil because it is generally in heat exchange relation withoutdoor air. In some instances, however, it is desirable that thevolumetric capacity of the inside coil be somewhat less than two-thirdsthat of the outside coil and in that event, during the time the insidecoil is serving as a condenser for producing a heating cycle, therefrigerant. capacity relative to the volume ofrefrigerant available tothe compressor results in the refrigerant pressure exceeding normaloperating pressures causing malfunction thereof.

The present invention contemplates the removal of a definite quantity ofrefrigerant from circulation to the compressor during the heating cycleby the provision of a refrigerant passage between the two exchangersincluding a refrigerant restrictor, such as a capillary tube, whichprovides the correct restriction to the flow of refrigerant in onedirection to provide for economical and efficient cooling of the insidecoil during the cooling cycle, and which passage also includes a liquidreservoir having a second refrigerant restrictor, such as a capillarytube, connected in series therewith, and a valving arrangement such thatduring the flow of refrigerant from the inside coil to the outside coilfor effecting a heating cycle, the refrigerant passes through the firstrestrictor, into the reservoir, then through the second restrictor tothe outside exchanger, but during the flow in the opposite direction forthe cooling cycle the refrigerant by-passes the'second restrictor andreservoir and passes directly to the first mentioned restrictor andthence to the inside coil.' By this arrangement, during the coolingcycles the full charge of refrigerant circulates in the system, but whenthe flow of refrigerant is reversed to provide for heating cycles, a

quantity of refrigerant equal to the-volumetric capacity of thereservoir is removed from circulation and an addi- .tional restrictionto the flow between the coils is effected. By locating the liquidreservoir between the two restrictors, complete filling of the reservoiris assured so that a definite amount of refrigerant is removed fromcirculation in the system. The volume of the liquid reservoir preferablyequals approximately the difference in volume of the indoor coiland'two-thirds the volume of the outdoor coil.

In carrying out the invention, the reservoir and second restrictor arearranged in shunt with a check valve which permits direct flow ofrefrigerant from the outdoor coil to the first restrictor during thecooling cycle of the heat pump system, but during the heating cycle thevalve is closed to direct'refrigerant flowing from the first restrictorinto the reservoir and then through the second restrictor to'increaserestriction to the flow and to remove a definite volume of liquidrefrigerant from the system.

Otherobjects and advantages of the invention will be apparent from thefollowing description of a preferred form, reference being made to theaccompanying drawings wherein Figs. 1 and 2 show schematically, areversible heat pump system embodying the invention, Fig. 1 showing thesystem according to the flow of refrigerant during the cooling cycle andFig. 2 showing the flow in the opposite direction.

Since the components comprising the invention and heat pump systems arewell known in the art, the invention is illustrated schematically forsake of clarity. Refer ring to the drawings, a conventional reversiblecycle heat pump system is shown of the compressor, condenser-expandertype and it includes a refrigerant compressor -10 having the dischargethereof connected by a pipe 11v to the intake of 'a reversing valve V.One reverse flow port of the reversing valve is connected by pipe 16 toone end of a coil type heat exchanger 17 which comprises a serpentinearranged tube 18 having a fin structure 19 assembled therewithcomprising closely spaced parallel fins so that air may be passedbetween the fins to provide good heat exchange between the air and therefrigerant in the tubes. The exchanger 17 is preferably located orarranged so that it is subjected to outdoor air and is hereinafterreferred to as the outdoor coil.

A second reverse flow port of reversing valve V is connected by a pipe20 to one end of a heat exchanger 21 which is similar to that describedwith reference to outdoor coil 17 having a serpentine coil 22 enclosedin a fin structure 23 of parallel, closely spaced fins, and which isdisposed to have air passed between the fins and discharged into anenclosure, such as a room, and for this reason this exchanger ishereinafter referred to as .the indoor coil.

Coils 18 and 22 are interconnected by a refrigerantpassage whichcomprises a first restrictor 25 in the form of a capillary tube havingone end connected with coil 22 and the other end connected with theoutlet of acheck valve 26 the inlet of which is connected with one endof coil 18. Check valve 26 permits flow of refrigerant from coil 18 torestrictor 25 but prevents flow from the restrictor to the coil so thatthis flow of refrigerant is forced to by-pass the check valve and flowinto a reservoir or tank 27, the bottom of which is connected withthe-right hand end of capillary tube 25 by a tube 28. The top of'tank 27is connected to one end of a second restrictor 29 which comprises acapillary tube, the other end of which is connected to coil 18 upstreamfrom check valve 26 relative to the flow from the coil through thevalve. By this --ar'- rangement, refrigerant flowing from coil 18 tocoil 22 passes through restrictor 25' and bypasses restrictor 29 andreservoir 27. Flow of-refrigerant in the' opposite'.direction, on theother hand, is throughre'strictor 2'5, 29 so that the restriction toflow in the latter direction is increased.

The volumetric capacity of tank 27 is preferably equal to thedifferences in volumetric capacity of the indoor coil and two-thirds thecapacity of the outdoor coil, the purpose of which is explainedhereinafter.

The intake of compressor is connected by a pipe 30 to the exhaust portof reversing valve V, which port is selectively connected with either ofthe reverse flow pipes 16 or 20 by a sliding shoe type valve member 31which is shifted in the valve body by suitable mechanism, not shownbecause such mechanisms are well known in the art. When valve member 31is in the position shown in Fig. l, which is the position for a coolingcycle, the discharge of the compressor is connected to the upper end ofoutdoor coil 18 and the suction or intake of the compressor is connectedto the upper end of indoor coil 18, through check valve 26 to restrictor25, which restricts the flow of gaseous refrigerant to causeliquification thereof, whereupon the liquid refrigerant flows into coil22 where it is vaporized and returned to the intake of the compressor.It will be apparent that restrictor 29 and reservoir 27 are by-passed bythe refrigerant and all liquid which might possibly be in the reservoiris drained therefrom and fed by syphon action into the system. Thus, thewhole of the refrigerant is circulated through the system during thecooling cycle.

When valve V is reversed to effect a heating cycle, that is by causingthe indoor coil 22 to function as a condenser, refrigerant then fiowsfrom the discharge of the compressor to valve V, through pipe 20 intocoil 22, to restrictor 25, and, due to the closure of check valve 26,refrigerant from the restrictor is forced upwardly through reservoir 27and thence through restrictor 29 to the lower end of outdoor coil 18.Restrictors'25 and 2 act to increase the pressure of the refrigerant toliquify the same so that reservoir 27 will be completely filled withliquid refrigerant before it passes through restrictor 29 to coil 18.Coil 18, receiving liquid refrigerant in its lower end, now functions asan evaporator, and the vaporized refrigerant is withdrawn through pipe16 and returned to the intake of the compressor through valve V and pipe30.

It will be seen that during the heating cycle, a definite amount ofliquid is removed from effective circulation in the system so that themost efficient volume is utilized, and when the cycle is shifted to thecooling phase, the pressure across the reservoir and restrictor 29 isequalized so that the liquid in the reservoir is syphoned into thesystem for eflicient operation during the cooling cycle. By thisarrangement, it will be apparent that a definite volume of refrigerantis removed from the system during the heating cycle and that the totalrestriction imposed upon the flow of refrigerant from coil 22 to coil 18is increased by directing the flow through restrictor 29 as well asrestrictor 25 so that the efficiency of the heat pump system during theheating cycle is relatively high. The proper diameters and lengths ofthe restrictor tubes depend upon various other factors in the system andcan be determined by those skilled in the art.

Although but one form of the invention has been shown, it is to beunderstood that other adaptations, modifications and uses could beemployed, all falling within the scope of the claims which follow.

I claim:

1. In a heat pump system comprising a refrigerant compressor and firstand second coil type heat exchangers connected with the compressor in arefrigerating circuit and including means to selectively reverse theorder of flow of refrigerant through the exchangers, means forming arefrigerant passage between said exchangers including a firstrestrictor, a liquid reservoir, a second restrictor connected in serieswith said reservoir, and means to direct refrigerant flow from saidfirst exchanger successively through said first restrictor, saidreservoir and second restrictor and to said second exchanger wherebysaid reservoir is filled to capacity with liquid and to cause the flowof refrigerant from said second exchanger to said first exchanger toby-pass said second restrictor and reservoir and to flow through saidfirst restrictor.

2. A heat pump system as defined in claim 1 in which the volumetriccapacity of the first heat exchanger is less than two-thirds thevolumetric capacity of the second heat exchanger, and the volumetriccapacity of said reservoir is about two-thirdsof the difference incapacities of the two exchangers.

3. In a heat pump system comprising a refrigerant compressor and firstand second coil type heat exchangers connected with the compressor in arefrigerating circuit and including means to selectively reverse theorder of flow of refrigerant through the exchangers, one end of thefirst exchanger .being connected to one end of the second exchangerthrough a refrigerant restrictor and a valve connected in seriestherewith, a liquid reservoir hav ing one end connected with saidrestrictor between said restrictor proper and valve, and a secondrestrictor connected at one end with said reservoir and at the other endwith said second exchanger at .a point whereby said reservoir and secondrestrictor forms a shunt refrigerant fiow circuit around said valve,said valve operative to close when the flow of refrigerant is from saidfirst exchanger and through the first mentioned restrictor to saidsecond exchanger and to open when the flow is from said second exchangerto said first exchanger.

4. In a heat pump system comprising a refrigerant compressor and firstand second coil type heat exchangers connected with the compressor in arefrigerating circuit and including means to selectively reverse theorderof flow of refrigerant through the exchangers, one end of the firstexchanger being connected to one end of the second exchanger through afirst capillary restrictor tube and a check valve connected in seriestherewith, a liquid reservoir having its lower end connected with saidrestrictor adjacent to said valve, and a second capillary tuberestrictor connected at one end with the top of said reservoir and atthe other end with said second exchanger at a point to thereby form aby-pass around said valve, said valve operative to close when the fiowof refrigerant is from said first exchanger and through the firstmentioned restrictor to said second exchanger and to open when the flowis from said second exchanger to said first ex changer.

5. In a heat pump system comprising a refrigerant compressor and firstand second coil type heat exchangers connected with the compressor in arefrigerating circuit and including means to selectively reverse theorder of flow of refrigerant through the exchangers, one end of thefirst exchanger being connected to one end of the second exchangerthrough a refrigerant restrictor and a valve connected in series, aliquid reservoir having one end connected with said restrictor betweensaid restrictor proper and valve, and a second restrictor connected withsaid reservoir and said second exchanger at a point to permit flow ofrefrigerant around said valve, said reservoir and second restrictorforming a shunt around said valve, said valve operative to close whenthe flow of refrigerant is from said first exchanger and through thefirst mentioned restrictor to said second exchanger, and to open whenthe flow is from said second exchanger to said first exchanger.

References Cited in the file of this patent UNITED STATES PATENTS

